AIR TIME

1987 mag was 330hp oval port, the one you have is rec heads which will work fine for 500hp. you have good parts to start. you should call or email DEAN GELLNER AT 216 398 8500 OR EMAIL AT [email protected]. he would go over the lower end of the motor to if theres a lot of hours. he would install new hyd roller cam kit since you have a flat tappet hyd cam. pocket porting heads, valve job, and a marine carb or custom race carb both marine. and either a stock single plan intake or a custom one. you would be at 500 to 550hp with the custom stuff maybe higher. I did that with my 502 it was stock 390hp at the prop you are 350hp at the prop. if you want aftermarket heads he can do that too. but I made just under 600hp. that same motor with a 850bg custom heads and bigger cam made 650hp then with custom 1050dom carb made 670hp. Dean is going to change cam/intake custom and we will pick up between 40 to 70 hp depends on cam. so I would give him a call his motors last a long time.

AIR TIME

sorry DAREDEVIL but for the 1st year they called them mag with the alpha drive it was 1987 then in 88 they started 454 330hp and mag 365hp with the good parts, I had looked at a baja 240 sport in 90 and it had the alpha drive said 454mag 330hp. that was the last year of the trs 370hp 454, thats the motor the 365 mag replaced and drive with the B1. now tell this guy to call DEAN.

MOBILEMERCMAN

The 87 454 magnum was a alpha drive motor and was basically a 330 with small heads. The next year 88 the Magnum came with a bravo and was a 365 with rectangle port heads.

I DIG IT !!

Man look what I started.

WaterJunkie

You guys are great!!

Mine is not 330. It has rectangle port heads etc. I just didn't know how many horse it was. If the efi model is 385 is making 20 more horse with just the fuel injection? I planned on exhaust intake and roller cam just didn't know how far that would get me. Tossed around the idea of a pro charger but a guy who's upholstery I'm doing said his mechanic near LOTO said he would install a procharger but seriously does not recomend them. Are they not any good?

jeffswav

Do the exhaust first. You need it for any cam upgrade. I have EMI with long risers with no silent choice. Do not get short risers if you plan on doing a cam upgrade. Exhaust will give you about 1 or 2 MPH on a stock engine. Good Luck!!

KAAMA

iTrader: (1)

Yeah to what he said! The Merc 454/365hp engine comes stock with all the good forged internals,......but the FIRST thing you need is a better breathing, aftermarket exhaust system such as a Stainless Marine, GIL, Dana or something comparable to those. An upgraded exhaust is the only way you are to make more TRUE HP in a naturally aspirated engine with other internal upgrades like a cam, head porting, intake manifolds, carbs, etc. If you really want it to RUN, then you gotta let'er breath out the exhaust FIRST before she will buck for you

If you simply bolt a blower on your 365, then you would not neccessarily need an upgraded exhaust system, however anytime you can add a better breathing exhaust system over the Merc stock exhaust is a HUGE improvement!

By the way, you do not need to change the heads on those 365's....just have them checked for cracks between the seats, then have them bowl/pocket ported while paying attention to the short side radius. "JimV" (Michigan) would be good for that 616-889-0928. Add a Holley 750cfm carb, single plane intake, roller rocker arms, then for a cam selection you can install a good hydraulic roller and HANG ON! For the custom cam I recommend "RMBuilder"/Bob Madara of Marine Kinetics in N.Y. 585-654-8583---he's the cam guru and will grind you a cam profile for your combination and specific application. Have fun.

chris-jack

man, i love this forum.

WaterJunkie

would the emi manifolds in the classifieds be a good set or are they basically just replacements for oem?

WaterJunkie

Scratch that last question... guess if I would have read the whole add the first time I would have seen they're not for use on engines with performance cams.